Preparation of carbon-carbon composites through the chemical vapor infiltration (CVI) process, utilizing CH₄ and C₂H₅OH as precursors, can effectively improve the deposition rate and produce highly structured pyrolytic carbon. Understanding the reaction mechanism is essential for computational fluid dynamics (CFD) studies. Chemical reaction mechanisms typically involve numerous free radicals and reactions, and manually constructing such mechanisms based on experimental data alone risks omitting critical species and reactions. Hence, in this research, a thorough gas-phase pyrolysis kinetic mechanism for the CH₄+C₂H₅OH+Ar system was developed using the reaction mechanism generator (RMG). This mechanism included 31 core species and 214 core reactions, accurately predicting the evolution of major species' formation and consumption. The simulation results were consistent with experimental observations. Through a detailed analysis of the kinetics and sensitivity of reactants and critical products, reactions influencing the formation and consumption of crucial species were identified. Reaction pathway analysis further clarified relationships among different species, identifying core species within the mechanism. By simplifying the detailed mechanism based on sensitivity and rection pathway analysis at 1373 K and 10 kPa, a gas-phase kinetic mechanism was derived, composed of 18 species and 44 reactions. This streamlined model substantially boosts computational efficiency while retaining key species, providing a more convenient foundation for further CFD studies and applications.